Nato is enforcing a UN resolution to protect civilians from Gaddafi forces.

"The Nato-led mission is on track. The pressure on Gaddafi is mounting and the rebels have been gaining strength and momentum. We need to see this through and we are in complete agreement that we will," Mrs Clinton said in Madrid.

'Retreat'

Speaking alongside Mrs Clinton, Spanish Foreign Minister Trinidad Jimenez said "Spain's and the international coalition's response is to maintain the unity and determination with which we have been working these past months".

Col Gaddafi made the threat in an audio message broadcast to tens of thousands of supporters gathered in a central Tripoli square on Friday.

His message comes after France confirmed it had supplied weapons to anti-government rebels, delivering arms to Berber tribal fighters near Tripoli.

In the broadcast, played via loudspeakers to gathered crowds in the capital's Green Square, he called on supporters to "march on the western mountains", the area where the weapons had been delivered.

Then he warned Europe that Libyans would seek revenge.

"These people [the Libyans] are able to one day take this battle [...] to Europe, to target your homes, offices, families, which would become legitimate military targets, like you have targeted our homes," he said.

"If we decide to, we are able to move to Europe like locusts, like bees. We advise you to retreat before you are dealt a disaster," he added.

His message come just days after the International Criminal Court issued arrest warrants for Col Gaddafi, his son Saif al-Islam and Libyan intelligence chief Abdullah al-Sanoussi for crimes against humanity.

International prosecutors allege government troops fired on civilian protesters during anti-Gaddafi street demonstrations earlier this year.

Friday's rally was one of the largest in recent times, says the BBC's Rupert Wingfield-Hayes, in Tripoli, and the message was the first time that Col Gaddafi had been heard of in days.